Known contact surgical devices which utilize laser light as energy for ablation or vaporization of tissue can generally be divided into two categories: devices which have a tip formed of a ceramic material such as YAG, sapphire or silica, different from the material of an optic fiber carrying laser light to the tip, and devices in which an end of the optic fiber itself is tapered or otherwise sculpted to a shape useful for surgical applications. Devices of both types offer unique advantages, but also pose certain problems in their manufacture and subsequent use.
The tip element can be manufactured in a wide range of shapes and sizes, but experience shows that for substantial rates of transfer of laser energy from the optic fiber to the tip, heating of the fiber/tip interface due to Fresnel losses requires cooling. Such cooling can be provided by a fluid flow to transfer heat from the interface. However, such devices tend to be cumbersome, restrict the surgeon's freedom of operation, and can increase the risk to the patient.
The tapered fiber end devices require no cooling because there is no abrupt change of refractive index at an interface where energy losses and localized heating can occur but, for practical reasons, there are limitations on the size and shape to which the fiber end can be formed. For surgically useful sizes, such tips can only be formed at the light delivery ends of relatively large fibers which tend to be inflexible.
Known devices in which laser light is conveyed through an optic fiber to a tip made of a material having a significantly different refractive index include Daikuzono U.S. Pat. No. 4,736,743, in which laser energy delivered from a conically tapered probe is used to vaporize tissue in local contact therewith. Another such surgical laser probe is taught in also Daikuzono U.S. Pat. No. 4,693,244.
There exists a need for a surgical device in which laser light is delivered from a laser energy source through an optic fiber to a tip element without the need for cooling an interface between the delivery end of the optic fiber and the laser light receiving end of the tip element.